Jack and I see this matter similarly. With respect to each of the three enumerated powers in play in the ACA litigation, there are limiting principles available to the Court that would allow it to uphold the minimum coverage provision while respecting the structural principle of a national government of limited, enumerated powers.

The Necessary and Proper Clause

1. Unlike other purchase mandates, including every hypothetical at oral argument on Tuesday, the minimum coverage provision prevents the unraveling of a market that Congress has clear authority to regulate. In light of the adverse selection problem, upholding the minimum coverage provision would not mean that Congress could issue whatever purchase mandates it wanted. Rather, a decision upholding the provision could hold narrowly that Congress may issue a purchase mandate when, but only when, such a mandate is reasonably (or substantially or closely) related to preventing the unraveling of a market that Congress is regulating in undeniably constitutional ways.

It does not matter if Congress contributed to the problem. That was true in Comstock as well. It could not be otherwise: Congress can prevent terrorist attacks on military bases notwithstanding the fact that Congress created the targets when it created the bases.

Using the Sweeping Clause would allow the Court to uphold the minimum coverage provision on very narrow grounds.

Using this clause would also have the virtue of being responsive to the main reason why Congress enacted the ACA. The problem is not millions of Americans who just want to be left alone but are being forced to buy something they do not want or need. The problem is 40 million Americans who desperately want health insurance but cannot afford it because they fall into the nongroup market. If someone loses a job, gets very sick, and does not qualify for Medicaid, she and her family may end up in serious financial peril.

The Commerce Clause

2. The minimum coverage provision addresses economic problems, not merely social problems that do not involve markets. In other words, Lopez and Morrison remain secure if the Court upholds the provision.

3. The economic problems addressed by the minimum coverage provision are interstate in scope. Collective action failures and interstate externalities impede the ability of the states to guarantee access to health insurance, prevent adverse selection, and prevent cost shifting by acting on their own. Insurers operate in multiple states and have fled from states that guarantee access to states that do not. Individuals have turned down better job opportunities in states that do not guarantee access because they cannot afford to lose their health insurance. Residents of one state access medical care in other states.

The SG may have declined to stress this limiting principle because some federal laws exceed it. But that should reassure the federalists on the Court, not concern them.

The Tax Power

4. As I wrote in a recent post introducing a new paper of mine, the minimum coverage provision respects the limits on the tax power. The difference between a tax and a penalty is the difference between the minimum coverage provision and a required payment of say, $10,000 that has a scienter requirement and increases with each month that an individual remains uninsured. Unlike the minimum coverage provision, such an exaction would be so coercive that it would raise little or no revenue. It would thus be beyond the scope of the tax power.

Liberty

5. The minimum coverage provision does not violate any individual rights, including bodily integrity and substantive due process more generally. These rights would be violated by a mandate to eat broccoli or exercise a certain amount. This limit would not be worth mentioning if these hypos did not keep coming up.

In sum, if the Court upholds the minimum coverage provision, there are several limiting principles that would preclude the federal government from issuing any and all individual mandates, purchase or otherwise.